Name Class Date. In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.

Transcription

1 Assessment Chapter Test A ork and Energy MULTIPLE CHOICE In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question. 1. In which of the following sentences is work used in the scientific sense of the word? a. Holding a heavy box requires a lot of work. b. A scientist works on an experiment in the laboratory. c. Sam and Rachel pushed hard, but they could do no work on the car. d. John learned that shoveling snow is hard work. 2. In which of the following sentences is work used in the everyday sense of the word? a. Lifting a heavy bucket involves doing work on the bucket. b. The force of friction usually does negative work. c. Sam and Rachel worked hard pushing the car. d. ork is a physical quantity. 3. A force does work on an object if a component of the force a. is perpendicular to the displacement of the object. b. is parallel to the displacement of the object. c. perpendicular to the displacement of the object moves the object along a path that returns the object to its starting position. d. parallel to the displacement of the object moves the object along a path that returns the object to its starting position. 4. ork is done when a. the displacement is not zero. b. the displacement is zero. c. the force is zero. d. the force and displacement are perpendicular. 5. hat is the common formula for work? a. F v c. Fd 2 b. Fd d. F 2 d 6. In which of the following scenarios is work done? a. A weightlifter holds a barbell overhead for 2.5 s. b. A construction worker carries a heavy beam while walking at constant speed along a flat surface. c. A car decelerates while traveling on a flat stretch of road. d. A student holds a spring in a compressed position. Holt Physics 33 Chapter Test

2 7. In which of the following scenarios is no net work done? a. A car accelerates down a hill. b. A car travels at constant speed on a flat road. c. A car decelerates on a flat road. d. A car decelerates as it travels up a hill. 8. hich of the following energy forms is associated with an object in motion? a. potential energy c. nonmechanical energy b. elastic potential energy d. kinetic energy 9. hich of the following energy forms is not involved in hitting a tennis ball? a. kinetic energy c. gravitational potential energy b. chemical potential energy d. elastic potential energy 10. hich of the following formulas would be used to directly calculate the kinetic energy of a mass bouncing up and down on a spring? a. KE 1 2 kx 2 c. KE 1 2 mv 2 b. KE 1 2 kx 2 d. KE 1 2 mv hich of the following equations expresses the work-kinetic energy theorem? a. ME i ME f c. KE b. net PE d. net KE 12. The main difference between kinetic energy and potential energy is that a. kinetic energy involves position, and potential energy involves motion. b. kinetic energy involves motion, and potential energy involves position. c. although both energies involve motion, only kinetic energy involves position. d. although both energies involve position, only potential energy involves motion. 13. hich form of energy is involved in weighing fruit on a spring scale? a. kinetic energy c. gravitational potential energy b. nonmechanical energy d. elastic potential energy 14. Gravitational potential energy is always measured in relation to a. kinetic energy. c. total potential energy. b. mechanical energy. d. a zero level. 15. hat are the units for a spring constant? a. N c. N m b. m d. N/m Holt Physics 34 Chapter Test

3 16. hich of the following is a true statement about the conservation of energy? a. Potential energy is always conserved. b. Kinetic energy is always conserved. c. Mechanical energy is always conserved. d. Total energy is always conserved. 17. hich of the following are examples of conservable quantities? a. potential energy and length b. mechanical energy and length c. mechanical energy and mass d. kinetic energy and mass 18. Friction converts kinetic energy to a. mechanical energy. c. nonmechanical energy. b. potential energy. d. total energy. 19. hich of the following is the rate at which work is done? a. potential energy c. mechanical energy b. kinetic energy d. power 20. A more powerful motor can do a. more work in a longer time interval. b. the same work in a shorter time interval. c. less work in a longer time interval. d. the same work in a longer time interval. SHORT ANSER 21. A car travels at a speed of 25 m/s on a flat stretch of road. The driver must maintain pressure on the accelerator to keep the car moving at this speed. hat is the net work done on the car over a distance of 250 m? 22. State, in words, the work-kinetic energy theorem. Holt Physics 35 Chapter Test

4 23. A child does 5.0 J of work on a spring while loading a ball into a spring-loaded toy gun. If mechanical energy is conserved, what will be the kinetic energy of the ball when it leaves the gun? PROBLEM 24. How much work is done on a bookshelf being pulled 5.00 m at an angle of 37.0 from the horizontal? The magnitude of the component of the force that does the work is 43.0 N. 25. hat is the average power output of a weightlifter who can lift 250 kg a height of 2.0 m in 2.0 s? Holt Physics 36 Chapter Test

5 TEACHER RESOURCE PAGE Fx m k F net F n Fn ( N N) ( N) ork and Energy CHAPTER TEST A (GENERAL) 1. c 11. d 2. c 12. b 3. b 13. d 4. a 14. d 5. b 15. d 6. c 16. d 7. b 17. c 8. d 18. c 9. b 19. d 10. c 20. b 21. The net work is zero (because the net force on the car is zero). 22. The net work done by the net force acting on an object is equal to the change in the kinetic energy of the object J J Given F 43.0 N d 5.00 m Fd (43.0 N)(5.00 M) 215 J k Given m 250 kg d 2.0 m t 2.0 s g 9.81 m/s 2 m gd t (250 kg)(9.81 m/s 2 )(2.0 m) 2.0 s k ork and Energy CHAPTER TEST B (ADVANCED) 1. b 2. a 3. b 4. d 5. c KE 1 2 mv ( kg)(40.0 m/s 2 ) 108 J 6. a 7. d 8. b 9. b PE mgh (1.0 kg)(9.81 m/s 2 )(1.0 m) 9.8 J 10. a 11. d 12. c KE f PE g,i mgh (3.00 kg)(9.81 m/s 2 )(1.00 m) 29.4 J 13. c m gd t (60.0 kg)(9.81 m/s 2 )(4.0 m) 4.2 s ork, in the scientific sense, is the product of the component of a force along the direction of displacement and the magnitude of the displacement. No work is done unless a force causes some displacement that is not perpendicular to the force. 15. gravitational potential energy 16. At the top of the fall, all the energy is gravitational potential energy. During the fall, gravitational potential energy decreases as it is transformed into kinetic energy. hen the pencil reaches the ground, all the energy is kinetic energy mv 2 i mgh i 1 2 kx 2 i 1 2 mv 2 f mgh f 1 2 kx 2 f 18. Definition of power: P t Definition of work: Fd d Definition of speed: v t Fv Alternative definition of power: P Fv Holt Physics 184 Chapter Test